Methods of treating urea cycle disorders and maple syrup urine disease

ABSTRACT

The present invention provides methods for the treatment of urea cycle disorders and Maple Syrup Urine Disease.

BACKGROUND OF THE INVENTION

Inborn errors of metabolism are a class of disorders arising fromcongenital disorders of metabolism. Many of the disorders are the resultof defects of single genes that code for enzymes important formetabolism of certain substrates. The reduced activity of the enzymesresults in accumulation of substrate to toxic levels which, in turn,leads to various symptoms depending on the substrate.

Deregulation of branched chain amino acid catabolism leads to an inbornerror of metabolism known as maple syrup urine disease (MSUD). MSUD,also referred to as Branched-Chain Keto Aciduria, is an autosomalrecessive disorder, typically diagnosed within 4-7 days after birth,with an incidence of approximately 1 in 185,000 live births. MSUD iscaused by mutations that result in a deficiency in the mitochondrialbranched-chain ketoacid dehydrogenase complex (BCKDC), resulting in theaccumulation of the BCAAs (leucine, valine, isoleucine) and theircorresponding α-keto acids (BCKAs) (α-ketoisocaproate,α-ketoisovalerate, and α-keto-β-methylvalarate) in cells and body fluidsin MSUD patients. As described in International Patent Publication No.WO2011011781, herein incorporated by reference, sodium phenylbutyrate isuseful in the treatment of MSUD. If left untreated MSUD patients develophigh BCAA levels and suffer from chronic and acute neurological damage,including low IQ, mental impairment (poor cognitive function), socialimpairment (poor executive function), and metabolic decompensation(seizures and coma), central respiratory failure, and death may follow.

Urea cycle disorder (UCD) is another disorder arising from an inbornerror of metabolism, with an approximate incidence of 1 in 30,000 birthsand are characterized by the accumulation of toxic levels of nitrogen asammonia and glutamate in the blood. In UCD, a mutation causes adeficiency in an enzyme of the urea acid cycle (for exampleN-acetylglutamate synthetase, carbamoyl phosphate synthetase I,ornithine transcarbamylase, argininosuccinic acid sythetase,argininosuccinic acid lyase, or arginase) and can result inlife-threatening neurological complications. Treatment with phenylaceticacid (PA), or its pro-drug phenylbutyrate (PB), removes excess nitrogenfrom the system as PA is acetylated to phenylacetylglutamine andexcreted through the kidneys. An immediate release formulation of sodiumphenylbutyrate (BUPHENYL®) has been approved for the treatment of UCD,and a modified release form of phenylbutyrate (RAVICTI®) has also beenapproved for the treatment of UCD.

Neuroinflammation and oxidative stress are underlying causes of variousneurodegenerative disorders such as Parkinson's disease. Sodiumphenylbutyrate has been shown to suppress both proinflammatory moleculesand reactive oxygen species (ROS) in activated glial cells indicatingthat it may be useful for the treatment of neurodegenerative disorderssuch as Parkinson's disease.

Spinal muscular atrophy (SMA) is an autosomal recessive neuromusculardisease, characterized by degeneration of the anterior horn cells of thespinal cord. All forms of SMA are caused by homozygous loss of thefunctional survival motor neuron (SMN1) gene resulting in insufficientlevels of the SMN protein. Sodium phenylbutyrate has been found to beeffective in enhancing SMN protein levels and the number ofSMN-containing nuclear structures. Accordingly, sodium phenylbutyratemay be effective for the treatment of SMA.

Dystonia is a neurological disorder involving sustained musclecontractions. Early-onset primary dystonia is the most common form ofhereditary dystonia and is caused by deletion of a glutamic acid residuenear the carboxyl-terminus of torsinA. Mutation in torsinA has beenfound to induce ER stress, and inhibit the cyclic adenosine-3′,5′-monophosphate (cAMP) response to the adenylate cyclase agonistforskolin. As described in Cho et al. PLoS One 2014, 9(11), pagee110086, both mechanins have been shown to be corrected by4-phenylbutyrate. These results suggest that sodium phenylbutyrate couldbe used in the treatment of dystonia.

Inclusion body myositis is a degenerative muscle disease characterizedby progressive weakness and wasting of muscles of the arms and legs.There are two general types of IBM: sporadic and hereditary. Asdescribed in Nogalska et al. Neurobiol. Dis. 2014, 65, pages 93-101,sodium phenylbutyrate has been shown to reverse lysosomal dysfunction inan in vitro model of inclusion-body myositis, involving cultured humanmuscle fibers. Sodium phenylbutyrate was shown to improve lysosomalactivity, decrease Aβ42 and its oligomers, decrease γ-secretaseactivity, and prevent muscle-fiber vacuolization. Accordingly, sodiumphenylbutyrate could be used in the treatment of sporadic inclusion bodymyositis.

The commercially available formulations of immediate release sodiumphenylbutyrate (e.g., BUPHENYL®) are unpalatable due to taste that ishighly unpleasant. Noncompliance due to the poor taste can lead toinsufficient dosing and suboptimal outcomes. The present inventionaddresses the need to improve patient compliance, by providing apalatable sodium phenylbutyrate formulation that is biologically activeand bioequivalent to BUPHENYL®.

SUMMARY OF THE INVENTION

The present invention features palatable pharmaceutical compositionsincluding sodium phenylbutyrate and methods for the treatment of inbornerrors of metabolism (e.g., MSUD or UCD) with such compositions.

Accordingly, the invention features pharmaceutical compositions for oraladministration containing sodium phenylbutyrate and a taste-maskcoating, e.g., a taste-mask coating is insoluble at the neutral pH ofthe mouth and soluble at the acidic pH of the stomach, methods ofmanufacturing such compositions, and uses thereof. A non-limitingexample of a taste-mask coating with these properties is a polymerformed from dimethylaminoethyl methacrylate, butyl methacrylate, andmethyl methacrylate (e.g., a cationic polymer such as Eudragit EPO). Insome embodiments, the dosage form of the composition may be a pluralityof small particles each having a taste-mask coating or a tablet thatincludes a taste-mask coating. Given the high doses of sodiumphenylbutyrate generally required for the treatment of inborne errors ofmetabolism such as UCD and MSUD, high drug loading formulations tominimize the amount of material a patient must ingest are desirable.

In some embodiments, the composition of the invention is a plurality ofspray layered particles or beads for oral administration. In someembodiments, the spray layered particle has a seed core or a substrateonto which a drug layer is coated followed by a taste-mask coat layer.In addition to these coats the composition may include other coats(e.g., seal coats, barrier coats). In some embodiments, the compositionincludes a particle containing at least 15% total weight sodium phenylbutyrate. In some embodiments, the composition includes a particlecontaining greater than 50% sodium phenyl butyrate. In some embodiments,the composition includes a particle including a taste-mask coat that isat least 5% but not more than 50% of the total weight of the particle.

In an aspect, the invention features a taste-masked pharmaceuticalcomposition (e.g., a taste-masked and immediate release composition)including sodium phenylbutyrate and a pharmaceutically acceptablecarrier, wherein (i) less than 15% (e.g., less than 10%, less than 5%,less than 1%) of the sodium phenylbutyrate in the composition dissolvesin a transfer dissolution test at neutral pH (e.g., pH 6-8, pH 6.5-7.5,pH of about 6, pH of about 7, pH of about 8, pH of about 6.8) over aperiod of 10 minutes; and (ii) at least 95% (e.g., at least 96%, atleast 97%, at least 98%, at least 99%) of the sodium phenylbutyrate inthe composition dissolves in a transfer dissolution test at an acidic pH(e.g., pH 1-5, pH 1-2, pH of about 1, pH of about 2, pH of about 3, pHof about 4, pH of about 5, pH of about 1.2) over a period of 60 minutes.

In some embodiments, the composition includes a taste-mask coatingincluding a coating that is insoluble at a neutral pH (e.g., pH >5) andsoluble at an acidic pH (e.g., pH <2) such as a polymer formed fromdimethylaminoethyl methacrylate, butyl methacrylate, and methylmethacrylate (e.g., Eudragit E PO). In some embodiments, the compositionincludes 5-50% by total weight (e.g., 5-15%, 10-25%, 20-30%, 25-35%,30-40%, 35-45%, or 40-50% by total weight or at least 5%, at least 10%,at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, atleast 40%, or at least 45% by total weight, or less than 10%, less than15%, less than 20%, less than 25%, less than 30%, less than 35%, lessthan 40%, less than 45%, or less than 50% by total weight) of thetaste-mask coating.

In some embodiments, the composition includes 15-60% by total weight(e.g., 20-30%, 25-35%, 30-40%, 35-45%, 40-50%, 45-55%, or 50-60% bytotal weight or at least 15%, at least 20%, at least 25%, at least 30%,at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, orat least 60% by total weight, or less than 20%, less than 25%, less than30%, less than 35%, less than 40%, less than 45%, less than 50%, lessthan 55%, or less than 60% by total weight) of sodium phenylbutyrate.

In some embodiments, the composition includes 3-10% by total weight(e.g., 3-5%, 4-6%, 5-7%, 6-8%, 7-9%, or 8-10% by total weight, or atleast 3%, at least 4%, at least 5%, at least 6%, at least 7%, at least8%, at least 9%, or at least 10% by total weight, or less than 3%, lessthan 4%, less than 5%, less than 6%, less than 7%, less than 8%, lessthan 9%, or less than 10% by total weight) of a binder (e.g.,hydroxypropyl methylcellulose such as HPMC E 5, hydroxypropylcellulose,polyvinylalcohol, polyvinylpyrrolidone).

In some embodiments, the composition includes 0.1-7% by total weight(e.g., 0.2-1%, 0.5-3%, 2-5%, 3-7%) of a plasticizer (e.g., polyethyleneglycol such as a polyethylene glycol having a molecular weight between5,000 and 7,000 such as PEG6000, or triethylcitrate). In someembodiments, the composition does not include a plasticizer.

In some embodiments, the composition includes 4-15% by total weight(e.g., 4-6%, 5-7%, 6-8%, 7-9%, or 8-10% by total weight, or at least 4%,at least 5%, at least 6%, at least 7%, at least 8%, or at least 9% totalweight, or less than 4%, less than 5%, less than 6%, less than 7%, lessthan 8%, less than 9%, or less than 10%) of a hydrated magnesiumsilicate (e.g., talc).

In some embodiments, the composition includes 1-5% by total weight(e.g., includes 3-4%, 3.5-4.5%, 4-5% by total weight, or at least 1%, atleast 2%, at least 3%, or at least 4% by total weight, or less than 2%,less than 3%, less than 4%, or less than 5% by total weight) of a sealcoat including a water soluble polymer such as a polyvinyl alcohol(e.g., Opadry such as Opadry Clear). In some embodiments, thecomposition does not include a seal coat.

In some embodiments of any of the foregoing compositions, thecomposition is formulated as taste-mask coated tablets (e.g., tabletsproduced using standard pharmaceutical excipients such as fillers,binders, glidants, lubricant; manufacturing processes such as blending,milling, dry granulation, wet granulation, compression; and coated witha taste-mask coating, e.g. a taste-mask coating including a polymerformed from dimethylaminoethyl methacrylate, butyl methacrylate, andmethyl methacrylate such as Eudragit EPO), taste-mask coatedmini-tablets (e.g., tablets with a diameter of less than 4 mm producedusing standard pharmaceutical excipients such as fillers, binders,glidants, lubricant; manufacturing processes such as blending, milling,dry granulation, wet granulation, compression; and coated with ataste-mask coating, e.g. a taste-mask coating including a polymer formedfrom dimethylaminoethyl methacrylate, butyl methacrylate, and methylmethacrylate such as Eudragit EPO), or taste-mask coated beads producedby spray-layering, extrusion spheronization, rotor granulation, or meltcongealing methods.

In another aspect, the invention features a pharmaceutical compositionfor oral administration of sodium phenylbutyrate including 15-60% bytotal weight (e.g., 20-30%, 25-35%, 30-40%, 35-45%, 40-50%, 45-55%, or50-60% by total weight or at least 15%, at least 20%, at least 25%, atleast 30%, at least 35%, at least 40%, at least 45%, at least 50%, atleast 55%, or at least 60% by total weight, or less than 20%, less than25%, less than 30%, less than 35%, less than 40%, less than 45%, lessthan 50%, less than 55%, or less than 60% by total weight) of the sodiumphenylbutyrate in a drug layer and 5-50% by total weight (e.g., 5-15%,10-25%, 20-30%, 25-35%, 30-40%, 35-45%, or 40-50% by total weight or atleast 5%, at least 10%, at least 15%, at least 20%, at least 25%, atleast 30%, at least 35%, at least 40%, or at least 45% by total weight,or less than 10%, less than 15%, less than 20%, less than 25%, less than30%, less than 35%, less than 40%, less than 45%, or less than 50% bytotal weight) of a taste-mask coating including a coating that isinsoluble at a neutral pH (e.g., pH >5) and soluble at an acidic pH(e.g., pH <2) such as a polymer formed from dimethylaminoethylmethacrylate, butyl methacrylate, and methyl methacrylate (e.g.,Eudragit E PO).

In some embodiments, the drug layer further includes 3-10% by totalweight (e.g., 3-5%, 4-6%, 5-7%, 6-8%, 7-9%, or 8-10% by total weight, orat least 3%, at least 4%, at least 5%, at least 6%, at least 7%, atleast 8%, at least 9%, or at least 10% by total weight, or less than 3%,less than 4%, less than 5%, less than 6%, less than 7%, less than 8%,less than 9%, or less than 10% by total weight) of a binder (e.g.,hydroxypropyl methylcellulose such as HPMC E 5, hydroxypropylcellulose,polyvinylalcohol, polyvinylpyrrolidone).

In some embodiments, the drug layer further includes 0.1-1% by totalweight (e.g., 0.2-0.6 or about 0.5%) of a plasticizer (e.g.,polyethylene glycol such as a polyethylene glycol having a molecularweight between 5,000 and 7,000 such as PEG6000, or triethylcitrate). Insome embodiments, the drug layer does not include a plasticizer.

In some embodiments, the taste-mask coating further includes 1-9% bytotal weight (e.g., 3-5%, 4-6%, 5-7%, 6-8%, or 7-9% by total weight, orat least 3%, at least 4%, at least 5%, at least 6%, at least 7%, or atleast 8% by total weight or less than 3%, less than 4%, less than 5%,less than 6%, less than 7%, less than 8%, or less than 9%) of aplasticizer (e.g., polyethylene glycol such as a polyethylene glycolhaving a molecular weight between 5,000 and 7,000 such as PEG6000, ortriethylcitrate).

In some embodiments, the taste-mask coating further includes 4-15% bytotal weight (e.g., 4-6%, 5-7%, 6-8%, 7-9%, or 8-10% by total weight, orat least 4%, at least 5%, at least 6%, at least 7%, at least 8%, or atleast 9% total weight, or less than 4%, less than 5%, less than 6%, lessthan 7%, less than 8%, less than 9%, or less than 10%) of a hydratedmagnesium silicate (e.g., talc).

In some embodiments, the taste-mask coating includes 5-30% by totalweight of a polymer formed from dimethylaminoethyl methacrylate, butylmethacrylate, and methyl methacrylate (e.g., Eudragit E PO). In someembodiments, a polymer formed from dimethylaminoethyl methacrylate,butyl methacrylate, and methyl methacrylate (e.g., Eudragit E PO)comprises 50-75% by weight of the taste-mask coating.

In some embodiments, the composition further includes 1-50% by totalweight (e.g., 1-10%, 5-15%, 10-20%, 15-25%, 20-30%, 25-35%, 30-40%,35-45%, or 40-50% by total weight, or at least 5%, at least 10%, atleast 15%, at least 20%, at least 25%, at least 30%, at least 35%, atleast 40%, at least 45%, at least 50% by total weight, or less than 5%,less than 10%, less than 15%, less than 20%, less than 25%, less than30%, less than 35%, less than 40%, less than 45%, less than 50% by totalweight) of a seed core (e.g., microcrystalline cellulose, sugar spheres,starch spheres, or other inert spherical pharmaceutically acceptablematerial).

In some embodiments, the composition further includes 1-5% by totalweight (e.g., includes 3-4%, 3.5-4.5%, 4-5% by total weight, or at least1%, at least 2%, at least 3%, or at least 4% by total weight, or lessthan 2%, less than 3%, less than 4%, or less than 5% by total weight) ofa seal coat including a water soluble polymer such as a polyvinylalcohol (e.g., Opadry such as Opadry Clear).

In some embodiments, the composition includes 5-50% (e.g., 5-35%.15-35%, 15-50%) by total weight of the taste-mask coating.

In some embodiments, the composition includes 15-60% (e.g., 15-35%,15-25%) by total weight of sodium phenylbutyrate.

In some embodiments, the pharmaceutical composition includes 44-46% bytotal weight cellulose pellets; 22-24% by total weight sodiumphenylbutyrate; 5-7% by total weight HPMC E5; 3-4% by total weight ofOpadry Clear; 4-6% by total weight of a PEG6000; 12-14% by total weightof a polymer formed from dimethylaminoethyl methacrylate, butylmethacrylate, and methyl methacrylate (e.g., Eudragit E PO); and 5-7% bytotal weight of talc.

In some embodiments the pharmaceutical composition includes about 45% bytotal weight cellulose pellets, about 23% by total weight sodiumphenylbutyrate, about 6% by total weight HPMC E5, about 3% by totalweight of Opadry Clear, about 5% by total weight of a PEG6000; about 13%by total weight of a polymer formed from dimethylaminoethylmethacrylate, butyl methacrylate, and methyl methacrylate (e.g.,Eudragit E PO), and about 6% by total weight of talc.

In another aspect, the invention features a pharmaceutical compositionincluding: a. 38-40% by total weight cellulose pellets; b. 8-20% bytotal weight sodium phenylbutyrate; c. 5-7% by total weight HPMC E5; d.3-4% by total weight of Opadry Clear; e. 5-7% by total weight ofPEG6000; f. 17-19% by total weight of a polymer formed fromdimethylaminoethyl methacrylate, butyl methacrylate, and methylmethacrylate (e.g., Eudragit E PO); and g. 8-10% by total weight oftalc.

In another aspect, the invention features a pharmaceutical compositionof including: a. about 39% by total weight cellulose pellets; b. about19% by total weight sodium phenylbutyrate; c. about 6% by total weightHPMC E5; d. about 3% by total weight of Opadry Clear; e. about 6% bytotal weight of PEG6000; f. about 18% by total weight of a polymerformed from dimethylaminoethyl methacrylate, butyl methacrylate, andmethyl methacrylate (e.g., Eudragit E PO); and g. about 9% by totalweight of talc.

In another aspect, the invention features a pharmaceutical compositionincluding: a. 44-46% by total weight cellulose pellets; b. 22-24% bytotal weight sodium phenylbutyrate; c. 5-7% by total weight HPMC E5; d.3-4% by total weight of Opadry Clear; e. 4-6% by total weight ofPEG6000; f. 12-14% by total weight of a polymer formed fromdimethylaminoethyl methacrylate, butyl methacrylate, and methylmethacrylate (e.g., Eudragit E PO); and g. 5-7% by total weight of talc.

In another aspect, the invention features a pharmaceutical compositionof including: a. about 45% by total weight cellulose pellets; b. about23% by total weight sodium phenylbutyrate; c. about 6% by total weightHPMC E5; d. about 3% by total weight of Opadry Clear; e. about 5% bytotal weight of PEG6000; f. about 13% by total weight of a polymerformed from dimethylaminoethyl methacrylate, butyl methacrylate, andmethyl methacrylate (e.g., Eudragit E PO); and g. about 6% by totalweight of talc.

In some embodiments, the pharmaceutical composition includes 44-46% bytotal weight cellulose pellets; 22-24% by total weight sodiumphenylbutyrate; 5-7% by total weight HPMC E5; 3-4% by total weight ofOpadry Clear; 2-4% by total weight of a PEG6000; 14-16% by total weightof a polymer formed from dimethylaminoethyl methacrylate, butylmethacrylate, and methyl methacrylate (e.g., Eudragit E PO); and 7-9% bytotal weight of talc.

In some embodiments the pharmaceutical composition includes about 45% bytotal weight cellulose pellets, about 23% by total weight sodiumphenylbutyrate, about 6% by total weight HPMC E5, about 3% by totalweight of Opadry Clear, about 3% by total weight of a PEG6000; about 15%by total weight of a polymer formed from dimethylaminoethylmethacrylate, butyl methacrylate, and methyl methacrylate (e.g.,Eudragit E PO), and about 8% by total weight of talc.

In another aspect, the invention features a pharmaceutical compositionincluding: a. 32-34% by total weight cellulose pellets; b. 15-17% bytotal weight sodium phenylbutyrate; c. 3-5% by total weight HPMC E5; d.2-3% by total weight of Opadry Clear; e. 3-4% by total weight ofPEG6000; f. 27-29% by total weight of a polymer formed fromdimethylaminoethyl methacrylate, butyl methacrylate, and methylmethacrylate (e.g., Eudragit E PO); and g. 13-15% by total weight oftalc.

In another aspect, the invention features a pharmaceutical compositionof including: a. about 33% by total weight cellulose pellets; b. about16% by total weight sodium phenylbutyrate; c. about 4% by total weightHPMC E5; d. about 2% by total weight of Opadry Clear; e. about 3% bytotal weight of PEG6000; f. about 28% by total weight of a polymerformed from dimethylaminoethyl methacrylate, butyl methacrylate, andmethyl methacrylate (e.g., Eudragit E PO); and g. about 14% by totalweight of talc.

In another aspect, the invention features a pharmaceutical compositionincluding: a. 15-17% by total weight cellulose pellets; b. 45-50% bytotal weight sodium phenylbutyrate; c. 4-6% by total weight HPMC E5; e.2-3% by total weight of PEG6000; f. 20-22% by total weight of a polymerformed from dimethylaminoethyl methacrylate, butyl methacrylate, andmethyl methacrylate (e.g., Eudragit E PO); and g. 7-9% by total weightof talc.

In another aspect, the invention features a pharmaceutical compositionof including: a. about 16% by total weight cellulose pellets; b. about48% by total weight sodium phenylbutyrate; c. about 5% by total weightHPMC E5; e. about 3% by total weight of PEG6000; f. about 21% by totalweight of a polymer formed from dimethylaminoethyl methacrylate, butylmethacrylate, and methyl methacrylate (e.g., Eudragit E PO); and g.about 8% by total weight of talc.

In another aspect, the invention features a pharmaceutical compositionincluding: a. 6-8% by total weight cellulose pellets; b. 65-70% by totalweight sodium phenylbutyrate; c. 6-8% by total weight HPMC E5; e. 1-3%by total weight of PEG6000; f. 12-14% by total weight of a polymerformed from dimethylaminoethyl methacrylate, butyl methacrylate, andmethyl methacrylate (e.g., Eudragit E PO); and g. 4-6% by total weightof talc.

In another aspect, the invention features a pharmaceutical compositionof including: a. about 7% by total weight cellulose pellets; b. about67% by total weight sodium phenylbutyrate; c. about 7% by total weightHPMC E5; e. about 2% by total weight of PEG6000; f. about 13% by totalweight of a polymer formed from dimethylaminoethyl methacrylate, butylmethacrylate, and methyl methacrylate (e.g., Eudragit E PO); and g.about 5% by total weight of talc.

In another aspect, the invention features a pharmaceutical compositionincluding: a. 4-6% by total weight cellulose pellets; b. 45-50% by totalweight sodium phenylbutyrate; c. 4-6% by total weight HPMC E5; e. 3-4%by total weight of PEG6000; f. 28-30% by total weight of a polymerformed from dimethylaminoethyl methacrylate, butyl methacrylate, andmethyl methacrylate (e.g., Eudragit E PO); and g. 11-13% by total weightof talc.

In another aspect, the invention features a pharmaceutical compositionof including: a. about 5% by total weight cellulose pellets; b. about47% by total weight sodium phenylbutyrate; c. about 5% by total weightHPMC E5; e. about 3% by total weight of PEG6000; f. about 29% by totalweight of a polymer formed from dimethylaminoethyl methacrylate, butylmethacrylate, and methyl methacrylate (e.g., Eudragit E PO); and g.about 12% by total weight of talc.

In another aspect, the invention features a pharmaceutical compositionincluding: a. 6-7% by total weight cellulose pellets; b. 60-65% by totalweight sodium phenylbutyrate; c. 8-10% by total weight HPMC E5; e. 2-3%by total weight of PEG6000; f. 15-17% by total weight of a polymerformed from dimethylaminoethyl methacrylate, butyl methacrylate, andmethyl methacrylate (e.g., Eudragit E PO); and g. 5-7% by total weightof talc.

In another aspect, the invention features a pharmaceutical compositionof including: a. about 7% by total weight cellulose pellets; b. about61% by total weight sodium phenylbutyrate; c. about 9% by total weightHPMC E5; e. about 3% by total weight of PEG6000; f. about 16% by totalweight of a polymer formed from dimethylaminoethyl methacrylate, butylmethacrylate, and methyl methacrylate (e.g., Eudragit E PO); and g.about 6% by total weight of talc.

In another aspect, the invention features a pharmaceutical compositionincluding: a. 4-6% by total weight cellulose pellets; b. 42-47% by totalweight sodium phenylbutyrate; c. 6-8% by total weight HPMC E5; e. 3-4%by total weight of PEG6000; f. 28-30% by total weight of a polymerformed from dimethylaminoethyl methacrylate, butyl methacrylate, andmethyl methacrylate (e.g., Eudragit E PO); and g. 11-13% by total weightof talc.

In another aspect, the invention features a pharmaceutical compositionof including: a. about 5% by total weight cellulose pellets; b. about45% by total weight sodium phenylbutyrate; c. about 7% by total weightHPMC E5; e. about 4% by total weight of PEG6000; f. about 29% by totalweight of a polymer formed from dimethylaminoethyl methacrylate, butylmethacrylate, and methyl methacrylate (e.g., Eudragit E PO); and g.about 12% by total weight of talc.

In some embodiments of any of the foregoing compositions, thecomposition is formulated as spray-layered beads. In some embodiments ofany of the foregoing compositions, the composition is formulated astaste-masked beads produced by extrusion/spheronization, rotorgranulation, or melt congeal methods.

In some embodiments, any of the foregoing compositions may be tested inan in vitro dissolution transfer test in which the composition issubjected to a neutral pH for a predetermined period of time and thentransferred to an acidic pH for a predetermined period of time. Therelease of sodium phenylbutyrate is monitored at each pH to determinethe rate of dissolution of the sodium phenylbutyrate from thecomposition.

In some embodiments of any of the foregoing compositions, less than 15%(e.g., less than 10%, less than 5%, less than 1%) of the sodiumphenylbutyrate in the composition is dissolved in a transfer dissolutiontest at neutral pH (e.g., pH 6-8, pH 6.5-7.5, pH of about 6.8) over aperiod of 10 minutes.

In some embodiments of any of the foregoing compositions, at least 95%of sodium phenylbutyrate in the composition is dissolved oncetransferred to an acidic pH (e.g., pH 1-5, pH 1-2, pH about 1.2) in atransfer dissolution test over a period of 60 minutes.

In some embodiments of any of the foregoing compositions, at least 95%of sodium phenylbutyrate in the composition is dissolved in a transferdissolution test at an acidic pH (e.g., pH 1-5, pH 1-2, pH about 1.2)over a period of 30 minutes.

In some embodiments of any of the foregoing compositions, uponadministration to a subject, the composition has equivalent distributionin plasma compared to BUPHENYL®. In some embodiments of any of theforegoing compositions, the composition is bioequivalent to BUPHENYL®.

In some embodiments of any of the foregoing compositions, uponadministration to a subject, the composition has greater sodiumphenylbutyrate levels in the plasma at 30 minutes compared to anmodified release formulation (e.g., RAVICTI®) of sodium phenylbutyrate.

In some embodiments of any of the foregoing compositions, thecomposition scores favorably in a taste test in comparison to BUPHENYL®.

The invention also features methods of manufacturing pharmaceuticalcompositions for oral administration containing sodium phenylbutyrateand a taste-mask coating, e.g., a taste-mask coating is insoluble at theneutral pH of the mouth and soluble at the acidic pH of the stomach.

In some embodiments of any of the foregoing compositions, the taste-maskcoated beads may be administered in a dosing vehicle with a viscosity ofapproximately 50-1750 centipoise (cP), e.g., to aid suspension anddosing of the beads. One type of suspending agent that can be used ismodified corn starch or a combination of modified food starch andmaltodextrin (e.g., THICK-IT). For example, any of the foregoingcompositions may be administered with approximately 1-4 teaspoons (tsp)of THICK-IT® added per 120 mL of water to achieve this viscosity range.An appropriate quantity of taste-masked beads can be added to theTHICK-IT® water mixture and agitated to suspend the beads just prior toadministration.

Other suspending agents may also be used as a dosing vehicle. Exemplarysuspending agents include agar, alginic acid, sodium carboxymethylcellulose, carrageenan, dextrin, gelatin, guar gum, hydroxyethylcellulose, hydroxypropyl cellulose, Hypromellose, methyl cellulose,polyethylene glycol, povidone, tragacanth, xanthan gum, or othersuspending agents known in the art.

Additionally, the dosing vehicle may further contain flavoring agents,fragrances, dyes (colors), sweeteners, anti-caking agents, glidants(flow enhancers), and lubricants.

In some embodiments of any of the foregoing compositions, the taste-maskcoated beads may have a volume-based particle size distribution in which90% of the beads in the composition are smaller than about 500 μM, i.e.DV₉₀ approximately 500 μm, (e.g., smaller than 500 μM, smaller than 400μM, smaller than 300 μM).

Accordingly, in another aspect, the disclosure provides a method ofmanufacturing a pharmaceutical composition including sodium phenylbutyrate by providing a core including cellulose pellets, applying afirst layer including sodium phenylbutyrate, hydroxypropylmethylcellulose (e.g., HPMC E 5), and polyethylene glycol (e.g., a PEGhaving a molecular weight between 5,000 and 7,000 such as PEG6000),applying a second layer including a polyvinyl alcohol (e.g., an Opadrysuch as Opadry Clear), and applying a third layer including a derivativeof methyacrylic acid (e.g., a polymer formed from the copolymerizationof dimethylaminoethyl methacrylate, butyl methacrylate, and methylmethacrylate such as Eudragit E PO), a polyethylene glycol (e.g., a PEGhaving a molecular weight between 5,000 and 7,000 such as PEG6000), andhydrated magnesium silicate (e.g., talc), thereby manufacturing apharmaceutical composition including sodium phenyl butyrate.

In some embodiments of the method, the final composition includes 1-50%by total weight (e.g., 0-10%, 5-15%, 10-20%, 15-25%, 20-30%, 25-35%,30-40%, 35-45%, or 40-50% by total weight, or at least 5%, at least 10%,at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, atleast 40%, or at least 45% by total weight, or less than 5%, less than10%, less than 15%, less than 20%, less than 25%, less than 30%, lessthan 35%, less than 40%, less than 45%, less than 50% by total weight)of cellulose pellets.

In some embodiments of the method, the final composition includes afirst layer including 15-60% by total weight (e.g., 20-30%, 25-35%,30-40%, 35-45%, 40-50%, 45-55%, or 50-60% by total weight, or at least15%, at least 20%, at least 25%, at least 30%, at least 35%, at least40%, at least 45%, at least 50%, at least 55% by total weight or lessthan 20%, less than 25%, less than 30%, less than 35%, less than 40%,less than 45%, less than 50%, less than 55%, or less than 60% by totalweight) of sodium phenylbutyrate, 3-10% by total weight (e.g., 3-5%,4-6%, 5-7%, 6-8%, 7-9, or 8-10% by total weight, or at least 3%, atleast 4%, at least 5%, at least 6%, at least 7%, at least 8%, or atleast 9% by total weight, or less than 3%, less than 4%, less than 5%,less than 6%, less than 7%, less than 8%, less than 9%, or less than 10%by total weight) of hydroxypropyl methylcellulose, and less than 1% bytotal weight (e.g., 0.001-0.1%, 0.01%-0.2%, 0.1-0.3%, 0.2-0.5%,0.4-0.6%, 0.5-0.7%, 0.6-0.8%, 0.7-0.9%, or 0.8-1.0% by total weight, orat least 0.001%, at least 0.01%, at least 0.1%, at least 0.2%, at least0.3%, at least 0.4%, at least 0.5%, at least 0.6%, at least 0.7%, atleast 0.8%, or at least 0.9% by total weight or less than 0.001%, lessthan 0.01%, less than 0.1%, less than 0.2%, less than 0.3%, less than0.4%, less than 0.5%, less than 0.6%, less than 0.7%, less than 0.8%,less than 0.9%, or less than 1% by total weight) of polyethylene glycol.

In some embodiments of the method, the final composition includes asecond layer including 3-5% by total weight (e.g., 3-4%, 3.5-4.5%, or4-5% by total weight, or at least 3%, at least 3.5%, at least 4%, or atleast 4.5%, or less than 3.5%, less than 4%, less than 4.5%, or lessthan 5% by total weight) of polyvinyl alcohol.

In some embodiments of the method, the final composition includes athird layer including 10-15% (e.g., 10-12%, 11-13%, 12-15%, or 14-15% bytotal weight, or at least 10%, at least 11%, at least 12%, at least 13%,or at least 14% by total weight, or less than 10%, less than 11%, lessthan 12%, less than 13%, less than 14%, or less than 15%) total weightof a polymer formed from dimethylaminoethyl methacrylate, butylmethacrylate, and methyl methacrylate (e.g., Eudragit E PO), 3-10% bytotal weight (e.g., 3-5%, 4-6%, 5-7%, 6-8%, 7-9, or 8-10% by totalweight, or at least 3%, at least 4%, at least 5%, at least 6%, at least7%, at least 8%, or at least 9% by total weight, or less than 3%, lessthan 4%, less than 5%, less than 6%, less than 7%, less than 8%, lessthan 9%, or less than 10%) of polyethylene glycol, and 4-15% (e.g.,4-6%, 5-7%, 6-8%, 7-9%, or 8-10% by total weight, or at least 4%, atleast 5%, at least 6%, at least 7%, at least 8%, or at least 9% by totalweight, or less than 4%, less than 5%, less than 6%, less than 7%, lessthan 8%, less than 9%, or less than 10% by total weight) of hydratedmagnesium silicate.

In some embodiments of any of the foregoing methods, the first layer isapplied in water.

In some embodiments of any of the foregoing methods, the second layer isapplied in water.

In some embodiments of any of the foregoing methods, the third layer isapplied in organic solvent such as a solution of acetone and isopropylalcohol.

In another aspect, the invention features a pharmaceutical compositionprepared by any of the foregoing methods.

In another aspect, the invention features a method of treating an inbornerror of metabolism (e.g., maple syrup urine disease or urea cycledisorder) in a subject including administering an effective amount ofany of the foregoing pharmaceutical compositions.

In another aspect, the invention features a method of treating aneurodegenerative disorder (e.g., Parkinson's disease) in a subjectincluding administering an effective amount of any of the foregoingpharmaceutical compositions.

In another aspect, the invention features a method of treating spinalmuscular atrophy in a subject including administering an effectiveamount of any of the foregoing pharmaceutical compositions.

In another aspect, the invention features a method of treating dystoniain a subject including administering an effective amount of any of theforegoing pharmaceutical compositions.

In another aspect, the invention features a method of treatinginclusion-body myositis in a subject including administering aneffective amount of any of the foregoing pharmaceutical compositions.

In some embodiments of any of the foregoing methods, the subject is ahuman.

In some embodiments of any of the foregoing methods, the pharmaceuticalcomposition is administered in a dosing vehicle with a viscosity ofapproximately 50-1750 centipoise (cP), e.g., to aid suspension anddosing of the beads. One type of suspending agent that can be used ismodified corn starch or a combination of modified food starch andmaltodextrin (e.g., THICK-IT®). For example, any of the foregoingcompositions may be administered with approximately 1-4 teaspoons (tsp)of THICK-IT® added per 120 mL of water to achieve this viscosity range.An appropriate quantity of taste-masked beads can be added to theTHICK-IT®/water mixture and agitated to suspend the beads just prior toadministration.

Other suspending agents may also be used as a dosing vehicle. Exemplarysuspending agents include agar, alginic acid, sodium carboxymethylcellulose, carrageenan, dextrin, gelatin, guar gum, hydroxyethylcellulose, hydroxypropyl cellulose, Hypromellose, methyl cellulose,polyethylene glycol, povidone, tragacanth, xanthan gum, or othersuspending agents known in the art.

Additionally, the dosing vehicle may further contain flavoring agents,fragrances, dyes (colors), sweeteners, anti-caking agents, glidants(flow enhancers), and lubricants.

Definitions

About: As used herein, the term “about” when used in the context of theamount of a component of a composition means +/−10% of the recitedvalue.

Administered in combination: As used herein, the term “administered incombination” or “combined administration” means that two or more agentsare administered to a subject at the same time or within an intervalsuch that there may be an overlap of an effect of each agent on thepatient. In some embodiments, they are administered within about 60, 30,15, 10, 5, or 1 minute of one another. In some embodiments, theadministrations of the agents are spaced sufficiently closely togethersuch that a combinatorial (e.g., a synergistic) effect is achieved.

Animal: As used herein, the term “animal” refers to any member of theanimal kingdom. In some, particularly therapeutic, embodiments, “animal”refers to humans at any stage of development. In some embodiments,“animal” refers to non-human animals at any stage of development. Incertain embodiments, the non-human animal is a mammal (e.g., a rodent, amouse, a rat, a rabbit, a monkey, a dog, a cat, a sheep, cattle, aprimate, or a pig). In some embodiments, animals include, but are notlimited to, mammals, birds, reptiles, amphibians, fish, and worms. Insome embodiments, the animal is a transgenic animal,genetically-engineered animal, or a clone.

Approximately: As used herein, the term “approximately”, as applied toone or more values of interest refers to a value that is similar to astated reference value. In certain embodiments, the term “approximately”or refers to a range of values that fall within 25%, 20%, 19%, 18%, 17%,16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%,or less in either direction (greater than or less than) of the statedreference value unless otherwise stated or otherwise evident from thecontext (except where such number would exceed 100% of a possiblevalue).

Binder: As used herein, the term “binder,” refers to an excipient thatholds the ingredients in a formulation together or holds ingredientsonto a substrate (e.g., the seed core). Binders ensure that tablets andgranules can be formed with required mechanical strength, and givevolume to low active dose tablets. Examples of binders include, but arenot limited to, hydroxypropylmethylcellulose such as HPMC E 5,saccharides and their derivatives, protein such as gelatin, sugaralcohols such as xylitol, sorbitol or maltitol, or synthetic polymerssuch as polyvinylpyrrolidone or polyethyleneglycol.

Bioequivalent: As used herein, the term “bioequivalent,” refers to theabsence of a significant difference in the rate and extent to which theactive ingredient or active moiety in pharmaceutical equivalents orpharmaceutical alternatives becomes available at the site of drug actionwhen administered at the same molar dose under similar conditions in anappropriately designed study. As understood by one of skill in the art,different types of evidence may be used to establish bioequivalence forpharmaceutically equivalent drug products, including in vivo (e.g., Cmaxand/or AUC data) or in vitro (e.g., rate of dissolution) testing, orboth. The selection of the method used to demonstrate bioequivalencedepends upon the purpose of the study, the analytical methods available,and the nature of the drug product. In some embodiments, bioequivalencemay be established using any method described herein such as determiningthe plasma levels of sodium phenylbutyrate of two different formulationsat different time points in healthy subjects.

Biologically active: As used herein, the phrase “biologically active”refers to a characteristic of any substance that has activity in abiological system and/or organism. For instance, a substance that, whenadministered to an organism, has a biological effect on that organism,is considered to be biologically active. In particular embodiments, apolynucleotide of the present invention may be considered biologicallyactive if even a portion of the polynucleotide is biologically active ormimics an activity considered biologically relevant.

By Total Weight: As used herein, the phrase “by total weight” refers tothe amount of an ingredient in the composition as a percentage of thetotal weight of the total composition including all ingredients.

Delivery: As used herein, “delivery” refers to the act or manner ofdelivering a compound, substance, entity, moiety, cargo or payload.

Dosing Vehicle: As used herein, “dosing vehicle” refers topharmaceutically acceptable excipients (e.g., thickeners or suspensionagents), or combinations thereof, that aid in the administration of apharmaceutical formulation.

Equivalent Distribution: As used herein, “equivalent distribution,”refers to distribution, e.g., as measured in plasma, of phenylbutyratefrom one formulation that is substantially similar (e.g., within 10%,within 5%, within 2%, within 1%) of the distribution of anotherformulation.

Modified Release Formulation: As used herein, “modified releaseformulation,” refers to a formulation of phenylbutyrate, or apharmaceutically acceptable salt thereof, in which the phenyl butyrateis released such that there is a significant difference in the rate(e.g., the rate is significantly slower) and extent of absorption of theactive pharmaceutical ingredient compared to BUPHENYL®. An approvedmodified release formulation of phenylbutyrate is Glycerolphenylbutyrate which is sold under the trade name RAVICTI® and approvedfor use in the treatment of UCD.

Formulation: As used herein, a “formulation” includes at least sodiumphenyl butyrate and a delivery agent.

Greater Distribution: As used herein, the term “greater distribution”refers to distribution, e.g., as measured in plasma, of phenylbutyratefrom one formulation that is greater than (e.g., at least 5% greater, atleast 10% greater, at least 20% greater, at least 50% greater) thedistribution of another formulation.

In vitro: As used herein, the term “in vitro” refers to events thatoccur in an artificial environment, e.g., in a test tube or reactionvessel, in cell culture, in a Petri dish, etc., rather than within anorganism (e.g., animal, plant, or microbe).

In vivo: As used herein, the term “in vivo” refers to events that occurwithin an organism (e.g., animal, plant, or microbe or cell or tissuethereof).

Lubricant: As used herein, the term “lubricant,” refers to a compoundthat prevents the ingredients in a formulation from clumping together,prevents clumping of the completed composition (e.g., of thespray-layered beads), or prevents sticking of ingredients to surfaces(e.g., equipment used in the manufacture and/or processing of thecomposition). Examples of lubricants include, but are not limited to,talc, silica, and fats such as vegetable stearin, magnesium stearate, orstearic acid.

Organic solvent: As used herein, “organic solvent,” refers to acarbon-based substance that dissolves a solute (a chemically differentliquid, solid, or gas), resulting in a solution, wherein the substanceis not water.

Pharmaceutically acceptable: The phrase “pharmaceutically acceptable” isemployed herein to refer to those compounds, materials, compositions,and/or dosage forms which are, within the scope of sound medicaljudgment, suitable for use in contact with the tissues of human beingsand animals without excessive toxicity, irritation, allergic response,or other problem or complication, commensurate with a reasonablebenefit/risk ratio.

Pharmaceutically acceptable excipients: The phrase “pharmaceuticallyacceptable excipient” or “pharmaceutically acceptable carrier,” as usedherein, refers any ingredient other than the compounds described herein(for example, a vehicle capable of suspending or dissolving the activecompound) and having the properties of being substantially nontoxic andnon-inflammatory in a patient. Excipients may include, for example:antiadherents, antioxidants, binders, coatings, compression aids,disintegrants, dyes (colors), emollients, emulsifiers, fillers(diluents), film formers or coatings, flavors, fragrances, glidants(flow enhancers), lubricants, preservatives, printing inks, sorbents,suspensing or dispersing agents, sweeteners, thickeners, and waters ofhydration. Exemplary excipients include, but are not limited to:butylated hydroxytoluene (BHT), calcium carbonate, calcium phosphate(dibasic), calcium stearate, croscarmellose, crosslinked polyvinylpyrrolidone, citric acid, crospovidone, cysteine, ethylcellulose,gelatin, hydroxypropyl cellulose, hydroxypropyl methylcellulose,lactose, magnesium stearate, maltitol, maltodextrin, mannitol,methionine, methylcellulose, methyl paraben, microcrystalline cellulose,polyethylene glycol, polyvinyl pyrrolidone, povidone, pregelatinizedstarch, propyl paraben, retinyl palmitate, shellac, silicon dioxide,sodium carboxymethyl cellulose, sodium citrate, sodium starch glycolate,sorbitol, starch (e.g., modified food or corn starch), stearic acid,sucrose, talc, titanium dioxide, vitamin A, vitamin E, vitamin C, andxylitol.

Pharmaceutically acceptable salts: The present disclosure also includespharmaceutically acceptable salts of the compounds described herein. Asused herein, “pharmaceutically acceptable salts” refers to derivativesof the disclosed compounds wherein the parent compound is altered byconverting an existing acid or base moiety to its salt form (e.g., byreacting the free base group with a suitable organic acid). Examples ofpharmaceutically acceptable salts include, but are not limited to,mineral or organic acid salts of basic residues such as amines; alkalior organic salts of acidic residues such as carboxylic acids; and thelike. Representative acid addition salts include acetate, adipate,alginate, ascorbate, aspartate, benzenesulfonate, benzoate, bisulfate,borate, butyrate, camphorate, camphorsulfonate, citrate,cyclopentanepropionate, digluconate, dodecylsulfate, ethanesulfonate,fumarate, glucoheptonate, glycerophosphate, hemisulfate, heptonate,hexanoate, hydrobromide, hydrochloride, hydroiodide,2-hydroxy-ethanesulfonate, lactobionate, lactate, laurate, laurylsulfate, malate, maleate, malonate, methanesulfonate,2-naphthalenesulfonate, nicotinate, nitrate, oleate, oxalate, palmitate,pamoate, pectinate, persulfate, 3-phenylpropionate, phosphate, picrate,pivalate, propionate, stearate, succinate, sulfate, tartrate,thiocyanate, toluenesulfonate, undecanoate, valerate salts, and thelike. Representative alkali or alkaline earth metal salts includesodium, lithium, potassium, calcium, magnesium, and the like, as well asnontoxic ammonium, quaternary ammonium, and amine cations, including,but not limited to ammonium, tetramethylammonium, tetraethylammonium,methylamine, dimethylamine, trimethylamine, triethylamine, ethylamine,and the like. The pharmaceutically acceptable salts of the presentdisclosure include the conventional non-toxic salts of the parentcompound formed, for example, from non-toxic inorganic or organic acids.The pharmaceutically acceptable salts of the present disclosure can besynthesized from the parent compound which contains a basic or acidicmoiety by conventional chemical methods. Generally, such salts can beprepared by reacting the free acid or base forms of these compounds witha stoichiometric amount of the appropriate base or acid in water or inan organic solvent, or in a mixture of the two; generally, nonaqueousmedia like ether, ethyl acetate, ethanol, isopropanol, or acetonitrileare preferred. Lists of suitable salts are found in Remington's TheScience and Practice of Pharmacy, 21^(st) Edition, A. R. Gennaro(Lippincott, Williams & Wilkins, Baltimore, Md., 2006); PharmaceuticalSalts: Properties, Selection, and Use, P. H. Stahl and C. G. Wermuth(eds.), Wiley-VCH, 2008, and Berge et al., Journal of PharmaceuticalScience, 66, 1-19 (1977), each of which is incorporated herein byreference in its entirety.

Pharmaceutically acceptable solvate: The term “pharmaceuticallyacceptable solvate,” as used herein, means a compound of the inventionwherein molecules of a suitable solvent are incorporated in the crystallattice. A suitable solvent is physiologically tolerable at the dosageadministered. For example, solvates may be prepared by crystallization,recrystallization, or precipitation from a solution that includesorganic solvents, water, or a mixture thereof. Examples of suitablesolvents are ethanol, water (for example, mono-, di-, and tri-hydrates),N-methylpyrrolidinone (NMP), dimethyl sulfoxide (DMSO),N,N′-dimethylformamide (DMF), N,N′-dimethylacetamide (DMAC),1,3-dimethyl-2-imidazolidinone (DMEU),1,3-dimethyl-3,4,5,6-tetrahydro-2-(1H)-pyrimidinone (DMPU), acetonitrile(ACN), propylene glycol, ethyl acetate, benzyl alcohol, 2-pyrrolidone,benzyl benzoate, and the like.

When water is the solvent, the solvate is referred to as a “hydrate.”

Plasticizer: As used herein, the term “plasticizer,” refers to anadditive that increases the plasticity or fluidity of a formulation.Plasticizers are used to control the film formation process of coatingsbased on physically drying film forming materials. Proper film formationis essential in order to meet demands on specific coating propertiessuch as dry film appearance, substrate adhesion, elasticity, incombination with high level of hardness at the same time. Examples ofplasticizers useful in the formulations and methods of the inventioninclude, but are not limited to, polyethylene glycols such as PEG6000 ortriethylcitrate.

Preventing: As used herein, the term “preventing” refers to partially orcompletely delaying onset of an infection, disease, disorder and/orcondition; partially or completely delaying onset of one or moresymptoms, features, or clinical manifestations of a particularinfection, disease, disorder, and/or condition; partially or completelydelaying onset of one or more symptoms, features, or manifestations of aparticular infection, disease, disorder, and/or condition; partially orcompletely delaying progression from an infection, a particular disease,disorder and/or condition; and/or decreasing the risk of developingpathology associated with the infection, the disease, disorder, and/orcondition.

Sample: As used herein, the term “sample” or “biological sample” refersto a subset of its tissues, cells or component parts (e.g. body fluids,including but not limited to blood, mucus, lymphatic fluid, synovialfluid, cerebrospinal fluid, saliva, amniotic fluid, amniotic cord blood,urine, vaginal fluid and semen). A sample further may include ahomogenate, lysate or extract prepared from a whole organism or a subsetof its tissues, cells or component parts, or a fraction or portionthereof, including but not limited to, for example, plasma, serum,spinal fluid, lymph fluid, the external sections of the skin,respiratory, intestinal, and genitourinary tracts, tears, saliva, milk,blood cells, tumors, organs. A sample further refers to a medium, suchas a nutrient broth or gel, which may contain cellular components, suchas proteins or nucleic acid molecule.

Scores favorably in a Taste Test: As used herein, the term “scoresfavorably in a taste test” refers to a formulation which scores higherin a taste test (e.g., any taste test known in the art) than anotherformulation. Different taste tests are known in the art, e.g.,formulations may be tested for palatability using any appropriate tastetest known in the art such by a flavor profile test. The flavor profilemethod uses trained evaluators, such as a panel of 1, 2, 3, 4, 5, 6, 7,8, 9, 10 or more experts, to identify, characterize, and quantify theperceived sensory attributes of a formulation. Attributes identified bythe panel are basic tastes (sweet, sour, salty, bitter, umami),aromatics (flavoring aromatics and aromatic “off-notes”), feelingfactors (cooling, numbing, bite/burn, etc.), and amplitude (perceptionof balance and fullness). The perceived strength or intensity of each ofthese attributes will be measured an assigned an appropriate value: 0for none, 1 for slight, 2 for moderate, and 3 for strong. Chemicalreference standards are used to establish the intensity scale foron-going panelist calibration. Additionally, all sensations remaining inthe aftertaste are measured at selected intervals over 1, 5, 10, 15 ormore minutes.

Seal coat: As used herein, the term “seal coat,” refers to a layer ofcompound(s) that prevents direct contact of two layers of thecomposition. In some embodiments, the seal coat protects the ingredientsin a formulation from deterioration by moisture in the air. In someembodiments, the seal coat protects the ingredients from deteriorationdue to contact with ingredients in another layer. Examples of compoundswhich may be used in a seal coat include, but are not limited to,Opadrys such as Opadry Clear, polyvinyl alcohols,hydroxypropylcellulose, hydroxypropylmethylcellulose, orpolyvinylpyrrolidone.

Seed core: As used herein, the term “seed core,” refers to a surface onwhich ingredients of a formulation may be applied. Examples of seedcores useful in the invention, include, but are not limited to,microcrystalline cellulose pellets, sugar spheres, starch spheres, orother inert spherical pharmaceutically acceptable materials. In someembodiments, the seed core is about 100 μm to 1.5 mm in diameter.

Significant or Significantly: As used herein, the terms “significant” or“significantly” are used synonymously with the term “substantially.”

Single unit dose: As used herein, a “single unit dose” is a dose of anytherapeutic administered in one dose/at one time/single route/singlepoint of contact, i.e., single administration event.

Spray-layered Bead: As used herein, the term “spray-layered bead” refersto spherical multiparticulates (e.g., 100- to 1,500-μm in size) with oneor more coating layers applied by fluidized-bead coating technology.Sucrose or microcrystalline substrates such as microcrystallinecellulose are typically utilized with the coat layers containing one ormore drug substances. Extruded beads or lipid multiparticulates may alsobe spray layered coated. In some embodiments, the multiparticulates arecomprise compressed drug substances which are then coated with one ormore layers (e.g., a taste-mask coat).

Subject: As used herein, the term “subject” or “patient” refers to anyorganism to which a composition in accordance with the invention may beadministered, e.g., for experimental, diagnostic, prophylactic, and/ortherapeutic purposes. Typical subjects include animals (e.g., mammalssuch as mice, rats, rabbits, non-human primates, and humans).

Substantially: As used herein, the term “substantially” refers to thequalitative condition of exhibiting total or near-total extent or degreeof a characteristic or property of interest. One of ordinary skill inthe biological arts will understand that biological and chemicalphenomena rarely, if ever, go to completion and/or proceed tocompleteness or achieve or avoid an absolute result. The term“substantially” is therefore used herein to capture the potential lackof completeness inherent in many biological and chemical phenomena.

Suffering from: An individual who is “suffering from” a disease,disorder, and/or condition has been diagnosed with or displays one ormore symptoms of a disease, disorder, and/or condition.

Susceptible to: An individual who is “susceptible to” a disease,disorder, and/or condition has not been diagnosed with and/or may notexhibit symptoms of the disease, disorder, and/or condition but harborsa propensity to develop a disease or its symptoms. In some embodiments,an individual who is susceptible to a disease, disorder, and/orcondition (for example, cancer) may be characterized by one or more ofthe following: (1) a genetic mutation associated with development of thedisease, disorder, and/or condition; (2) a genetic polymorphismassociated with development of the disease, disorder, and/or condition;(3) increased and/or decreased expression and/or activity of a proteinand/or nucleic acid associated with the disease, disorder, and/orcondition; (4) habits and/or lifestyles associated with development ofthe disease, disorder, and/or condition; (5) a family history of thedisease, disorder, and/or condition; and (6) exposure to and/orinfection with a microbe associated with development of the disease,disorder, and/or condition. In some embodiments, an individual who issusceptible to a disease, disorder, and/or condition will develop thedisease, disorder, and/or condition. In some embodiments, an individualwho is susceptible to a disease, disorder, and/or condition will notdevelop the disease, disorder, and/or condition.

Taste-mask coat: As used herein, the term “taste-mask coat,” refers to alayer of compound(s) that prevents release of the sodium phenylbutyratein the oral cavity and allow its release in the stomach to mask theunpleasant taste of sodium phenylbutyrate. In some embodiments, ataste-mask coating refers to a layer of compound(s) that results in aformulation that scores favorably in a taste test. Examples of compoundsuseful in taste-mask coats for the formulations and methods of theinvention include, but are not limited to, a polymer formed fromdimethylaminoethyl methacrylate, butyl methacrylate, and methylmethacrylate (e.g., Eudragit E PO) and other coatings that dissolve atthe pH of the stomach, but are insoluble at the pH of the mouth.

Therapeutic Agent: The term “therapeutic agent” refers to any agentthat, when administered to a subject, has a therapeutic, diagnostic,and/or prophylactic effect and/or elicits a desired biological and/orpharmacological effect.

Therapeutically effective amount: As used herein, “therapeuticallyeffective amount” refers to the amount of a compound that, whenadministered to a mammal for treating a state, disorder or condition(e.g., an inborn error of metabolism, such as MSUD), is sufficient toeffect such treatment. The “therapeutically effective amount” will varydepending on the compound, the disease and its severity, and the age,weight, physical condition and responsiveness of the mammal to betreated. As used herein the term “therapeutically effective amount”refers to an amount of a compound sufficient to prevent, inhibit,reduce, or eliminate one or more causes, symptoms, or complications ofelevated plasma levels of branched chain amino acids and/or branchedchain alpha-ketoacids (e.g., levels in an individual with an inbornerror of metabolism, such as MSUD) compared to the plasma levels in asubject that does not have an inborn error of metabolism (e.g., ahealthy subject and/or a subject with normal levels of branched chainamino acids and/or branched chain alpha-ketoacid). In certainembodiments, a desired therapeutic effect is the attainment of targetplasma levels (e.g., 200-500 μmol/L leucine, 100-200 μmol/L isoleucine,and 100-300 μmol/L valine) of at least one branched chain amino acidand/or branched chain alpha-ketoacid for the individual. In certainembodiments, a desired therapeutic effect is the attainment of normalplasma levels (e.g., 65-220 μmol/L leucine, 26-100 μmol/L isoleucine,and 90-300 μmol/L valine) of at least one branched chain amino acid. Inspecific embodiments, the treatment is considered therapeuticallyeffective when there is a particular extent of reduction in the plasmalevel of one or more branched chain amino acids and/or branched chainalpha-ketoacids. In certain cases, the treatment is consideredtherapeutically effective when there is a reduction of at least 5%,7.5%, 10%, 12.5%, 15%, 17.5%, 20%, 22.5%, 25%, 27.5%, 30%, 32.5%, 35%,37.5%, 40%, 42.5%, 45%, 47.5%, or 50% of the plasma level of one or morebranched chain amino acids and/or branched chain alpha-ketoacids or whenthere is a reduction of at least about 5%, 7.5%, 10%, 12.5%, 15%, 17.5%,20%, 22.5%, 25%, 27.5%, 30%, 32.5%, 35%, 37.5%, 40%, 42.5%, 45%, 47.5%,or 50% of the plasma level of one or more branched chain amino acidsand/or branched chain alpha-ketoacids. The skilled artisan recognizesthat plasma levels may be measured by standard methods in the art, forexample using a plasma amino acid test or urine amino acid test bychromatography and/or mass spectrometry.

Total daily dose: As used herein, a “total daily dose” is an amountgiven or prescribed in 24 hr period. It may be administered as a singleunit dose.

Transfer dissolution test: As used herein, the term “transferdissolution test” refers to an in vitro test of the release of sodiumphenylbutyrate from a formulation. The dissolution of sodiumphenylbutyrate may be determined using any method in the art. Forexample, the dissolution of sodium phenylbutyrate in a formulation ofsodium phenylbutyrate, may be determined following the dissolution assayprotocol described below.

A pH 6.8 potassium phosphate buffer solution (USP) was prepared, and 700mL of the solution was added to a Distek 2500 USP II (paddle)dissolution apparatus. The bath was heated to 37.5 C and 1 gm of sodiumphenylbutyrate multiparticulates was added while being agitated at 100RPM. Samples of the dissolution media (1.5 mL) were collected at t=5, 10and 15 minutes. After the 15 minute sample was taken 100 mL of 1 Nhydrochloric acid solution was added to the dissolution vessel, and thevolume was adjusted to 900 mL by adding a pH 1.2 0.1 N HCl solution(USP). The dissolution test continued for another 65 minutes, and 1.5 mLsamples were collected at t=20, 30, 40, 50, 60, 70 and 80 minutes. Afterthe 80 minute sample was taken the agitation was increased to 300 RPMfor an additional 15 minutes, and a final 1.5 mL sample was taken att=95 minutes. A Shimadzu Prominence-I LC-2030C 3D HPLC system was usedto measure the drug release in all samples.

Treating: As used herein, “treating” or “treatment” of a state, disorderor condition includes: (1) preventing or delaying the appearance ofclinical symptoms of the state, disorder or condition developing in amammal that may be afflicted with or predisposed to the state, disorderor condition, but does not yet experience or display clinical orsubclinical symptoms of the state, disorder or condition; (2) inhibitingthe state, disorder or condition, i.e., arresting or reducing thedevelopment of the disease or at least one clinical or subclinicalsymptom thereof; or (3) relieving the disease, i.e., causing regressionof the state, disorder or condition or at least one of its clinical orsubclinical symptoms.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A is a schematic of a taste-masked particle with a seed core.

FIG. 1B is a schematic of a taste-masked particle with a drug containingcore.

FIG. 1C is a schematic of a taste-masked tablet.

FIG. 2 is a graph illustrating drug release in a transfer dissolutiontest over time.

FIG. 3 is a graph illustrating drug release in a transfer dissolutiontest over time.

FIG. 4 is a graph illustrating drug release in a transfer dissolutiontest over time.

FIG. 5 is a graph illustrating drug release in a transfer dissolutiontest over time.

FIG. 6 is a graph illustrating drug release in a transfer dissolutiontest over time.

FIG. 7 is a graph illustrating drug release in a transfer dissolutiontest over time.

FIG. 8 is a graph illustrating drug release in a transfer dissolutiontest over time.

DETAILED DESCRIPTION OF THE INVENTION

The invention described herein features taste-masked formulations ofsodium phenylbutyrate and methods of using the formulations in thetreatment of inborn errors of metabolism such as MSUD and UCD,neurodegenerative disorders such as Parkinson's disease, spinal muscularatrophy, inclusion-body myositis, or dystonia. The formulations ofsodium phenylbutyrate of the invention address known issues withtreatment noncompliance, due to poor taste, and consequent insufficientdosing with commercially available formulations of sodium phenylbutyratesuch as BUPHENYL®. The formulations of the invention are taste-masked,pH sensitive formulations with rapid distribution of the activeingredient, sodium phenylbutyrate, e.g., as measured in the plasma of asubject. In some embodiments, the formulations include a high drug load.

Methods of Producing Taste-Masked Compositions

Taste-masked materials may be prepared by first identifying a suitableseed core such as cellulose pellets, followed by preparation of asolution including sodium phenylbutyrate. The sodium phenylbutyratecontaining solution may be prepared by combing in a solution of HPMC E 5and PEG 6000 in purified water with a separate solution of sodiumphenylbutyrate in purified water. The sodium phenylbutyrate-containinglayer is than applied to the seed core by spraying, followed by dryingand storage of the coated pellets.

A seal coat solution is prepared by mixing Opadry Clear in purifiedwater, followed by application onto the dried drug-containing pellets byspraying. The pellets with the seal coat are then dried and stored.

A taste mask coating solution is then prepared in a 2:3 partsacetone:IPA solution to which a polymer formed from dimethylaminoethylmethacrylate, butyl methacrylate, and methyl methacrylate (e.g.,Eudragit E PO) is added. The solution containing a polymer formed fromdimethylaminoethyl methacrylate, butyl methacrylate, and methylmethacrylate (e.g., Eudragit E PO) is then combined with anothersolution containing homogenized talc and PEG 6000.

The taste-mask coating solution is then applied to the seal coatedpellets by spraying. Subsequent drying of the pellets results in thefinished powder taste-masked formulation. In some embodiments, the finalcomposition (e.g., spray-layered beads) is blended with a lubricant suchas silica, e.g., to prevent agglomeration of the composition.

Prior to administration, the taste-masked formulation may be combinedwith a dosing vehicle that contains various pharmaceutically acceptableexcipients such as viscosity modifiers, suspending or dispering agents,flavoring agents, fragrances, dyes (colors), sweeteners, anti-cakingagents, glidants (flow enhancers), and lubricants.

The dosing vehicle may be mixed with the taste-masked formulation andadded to water and stirred, or the dosing vehicle may be added first tothe water and mixed before addition of the taste-masked formulation.

Other palatable liquids may be used instead of water provided that thepH of the liquid is ≥6.

Methods of Treatment

The present invention features pharmaceutical compositions in an orallytolerable formula that contains a therapeutically effective amount ofsodium phenylbutyrate. In some embodiments the pharmaceuticalcomposition is a granular formulation that is dispersed in apharmaceutically acceptable carrier, for example the composition can bemixed into water and ingested by a patient (e.g., over the course of 5to 10 minutes). Suitable formulations for use in the present inventionare found in Remington's Pharmaceutical Sciences, Mack PublishingCompany, Philadelphia, Pa. 22^(nd) ed., 2010. Except insofar as anyconventional carrier is incompatible with the active ingredient, its usein the pharmaceutical compositions is contemplated. Moreover, for animal(e.g., human) administration, it will be understood that preparationsshould meet sterility, pyrogenicity, general safety and purity standardsas required by FDA Office of Biological Standards.

The actual dosage amount of a composition of the present inventionadministered to a patient can be determined by physical andphysiological factors such as body weight, severity of condition, thetype of disease being treated, previous or concurrent therapeuticinterventions, idiopathy of the patient and on the route ofadministration. Depending upon the dosage and the route ofadministration, the number of administrations of a preferred dosageand/or an effective amount may vary according to the response of thesubject. The practitioner responsible for administration will, in anyevent, determine the concentration of active ingredient(s) in acomposition and appropriate dose(s) for the individual subject.

Maple Syrup Urine Disease

For the treatment of MSUD the actual dosage amount can be determined, inpart, by measuring the levels of branched chain amino acids (BCAAs) inthe plasma and adjusting dosage to decrease the plasma level of at leastone BCAA to within a range that is accepted to be non-toxic and supportsoptimal growth and development (Table 1).

TABLE 1 Target Ranges for BCAAs Branched Chain Target Levels NormalReference Amino Acid (μmol/L) Range (μmol/L) Leucine 200-500 65-220Isoleucine 100-200 26-100 Valine 100-300 90-300

Urea Cycle Disorders

Sodium phenyl butyrate is approved as an adjunctive therapy in thechronic management of subjects with UCD. Sodium phenylbutyrate isindicated for all patients with neonatal-onset deficiency and subjectswith late-onset disease who have a history of hyperammonemicencephalopathy. Sodium phenylbutyrate is generally administered incombination with dietary protein restriction and often with essentialamino acids supplementation.

The usual total daily dose of BUPHENYL® Tablets and Powder for patientswith urea cycle disorders is 450-600 mg/kg/day in patients weighing lessthan 20 kg, or 9.9-13.0 g/m²/day in larger patients. The tablets andpowder are to be taken in equally divided amounts with each meal orfeeding (i.e., three to six times per day). In some embodiments, thepharmaceutical compositions of the present invention are bioequivalentto BUPHENYL® and, therefore, equivalent dosage of sodium phenylbutyratewould be likely be useful for the treatment of UCD.

Spinal Muscular Atrophy

Sodium phenyl butyrate has been investigated as a treatment for infantswith spinal muscular atrophy. The target dose of BUPHENYL® powder forpatients with spinal muscular atrophy is 450-600 mg/kg/day, divided intofour doses. In some embodiments, the pharmaceutical compositions of thepresent invention are bioequivalent to BUPHENYL® and, therefore,equivalent dosage of sodium phenylbutyrate would be likely be useful forthe treatment of spinal muscular atrophy.

Parkinson's Disease

For the treatment of Parkinson's disease the actual dosage amount can bedetermined, in part, by measuring the levels of biomarkers (e.g., theexpression level of the gene DJ-1 as described in Zhou W. et al. J.Biol. Chem. 2011, 286(17), pages 14941-14951) in the blood and adjustingdosage accordingly (e.g., to increase the expression level of DJ-1without resulting in side effects).

Inclusion-Body Myositis

For the treatment of inclusion-body myositis, the actual dosage amountcan be determined by measuring the levels of biomarkers, e.g., bymeasuring the lysosomal activity, amount of Aβ42 and its oligomers,γ-secretase activity, and/or muscle-fiber vacuolization as described inNogalska et al.

Dystonia

For the treatment of dystonia, the actual dosage amount can bedetermined by measuring the levels of biomarkers, e.g., by measuring ERstress and/or the cyclic adenosine-3′, 5′-monophosphate (cAMP) responseto the adenylate cyclase agonist forskolin as described in Cho et al.

Dosages

The dosage of any composition described herein or identified using themethods described herein depends on several factors, including: theadministration method, the disease (e.g., MSUD, UCD, Parkinson'sdisease, spinal muscular atrophy, inclusion-body myositis, or dystonia)to be treated, the severity of the disease, and the age, weight, andhealth of the subject to be treated.

With respect to the treatment methods of the invention, it is notintended that the administration of a composition to a subject belimited to a particular dosage, or frequency of dosing. The compositionmay be administered to the subject in a single dose or in multipledoses. For example, a composition described herein may be administeredat least once a day (e.g., twice a day, three times a day, four times aday, or more). It is to be understood that, for any particular subject,specific dosage regimes should be adjusted over time according to theindividual need and the professional judgment of the personadministering or supervising the administration of the composition. Forexample, the dosage of a composition can be increased if the lower dosedoes not provide sufficient activity in the treatment of a disease orcondition described herein (e.g., MSUD, UCD, Parkinson's disease, spinalmuscular atrophy, inclusion-body myositis, or dystonia). Conversely, thedosage of the composition can be decreased if the disease (e.g., MSUD,UCD, Parkinson's disease, spinal muscular atrophy, inclusion-bodymyositis, or dystonia) is reduced.

While the attending physician ultimately will decide the appropriateamount and dosage regimen, a therapeutically effective amount of acomposition described herein, may be, for example, in the range ofapproximately 450-600 mg/kg/day of sodium phenylbutyrate (e.g., acomposition including 50% by weight sodium phenylbutyrate would requirea dose of 900-1200 mg/kg/day to provide 450-600 mg/kg/day of sodiumphenylbutyrate) for urea cycle disorder patients weighing less than 20kg, or 9.9-13.0 g/m²/day in larger patients. In some embodiments thetotal daily dosage is to be taken in equally divided amounts with eachmeal or feeding (i.e., three to six times per day).

In some embodiments a therapeutically effective amount of a compositiondescribed herein, may be, for example, in the range of approximately450-600 mg/kg/day of sodium phenylbutyrate (e.g., a compositionincluding 50% by weight sodium phenylbutyrate would require a dose of900-1200 mg/kg/day to provide 450-600 mg/kg/day of sodiumphenylbutyrate) in MSUD patients weighing less than 20 kg, or 9.9-13.0g/m²/day in larger patients. In some embodiments the total daily dosageis to be taken in equally divided amounts with each meal or feeding(i.e., three to twelve times per day).

Solid Dosage Forms for Oral Use

Formulations for oral use include particles containing the activeingredient(s) in a mixture with non-toxic pharmaceutically acceptableexcipients, and such formulations are known to the skilled artisan(e.g., U.S. Pat. Nos. 5,817,307, 5,824,300, 5,830,456, 5,846,526,5,882,640, 5,910,304, 6,036,949, 6,036,949, 6,372,218, herebyincorporated by reference). Some examples of solid dosage forms areshown in FIG. 1. Excipients may be, for example, inert diluents orfillers (e.g., sucrose, sorbitol, sugar, mannitol, microcrystallinecellulose, starches including potato starch, calcium carbonate, sodiumchloride, lactose, calcium phosphate, calcium sulfate, or sodiumphosphate); granulating and disintegrating agents (e.g., cellulosederivatives including microcrystalline cellulose, starches includingpotato starch, croscarmellose sodium, alginates, or alginic acid);binding agents (e.g., sucrose, glucose, sorbitol, acacia, alginic acid,sodium alginate, gelatin, starch, pregelatinized starch,microcrystalline cellulose, magnesium aluminum silicate,carboxymethylcellulose sodium, methylcellulose, hydroxypropylmethylcellulose, ethylcellulose, polyvinylpyrrolidone, or polyethyleneglycol); and lubricating agents, glidants, and anti-adhesives (e.g.,magnesium stearate, zinc stearate, stearic acid, silicas, hydrogenatedvegetable oils, or talc). Other pharmaceutically acceptable excipientscan be colorants, flavoring agents, plasticizers, humectants, andbuffering agents. In some embodiments, excipients (e.g., flavoringagents) are packaged with the composition. In some embodiments,excipients (e.g., flavorings) are packaged separately from thecomposition (e.g., are combined with the composition prior toadministration).

The solid compositions of the invention may include a coating adapted toprotect the composition from unwanted chemical changes, (e.g., chemicaldegradation prior to the release of the active substances). The coatingmay be applied on the solid dosage form in a similar manner as thatdescribed in Encyclopedia of Pharmaceutical Technology, supra.

Powders and granulates may be prepared using the ingredients mentionedabove in a conventional manner using, e.g., a mixer, a fluid bedapparatus, melt congeal apparatus, rotor granulator,extrusion/spheronizer, or spray drying equipment.

EQUIVALENTS AND SCOPE

Those skilled in the art will recognize, or be able to ascertain usingno more than routine experimentation, many equivalents to the specificembodiments in accordance with the invention described herein. The scopeof the present invention is not intended to be limited to the aboveDescription, but rather is as set forth in the appended claims.

In the claims, articles such as “a,” “an,” and “the” may mean one ormore than one unless indicated to the contrary or otherwise evident fromthe context. Claims or descriptions that include “or” between one ormore members of a group are considered satisfied if one, more than one,or all of the group members are present in, employed in, or otherwiserelevant to a given product or process unless indicated to the contraryor otherwise evident from the context. The invention includesembodiments in which exactly one member of the group is present in,employed in, or otherwise relevant to a given product or process. Theinvention includes embodiments in which more than one, or all of thegroup members are present in, employed in, or otherwise relevant to agiven product or process.

It is also noted that the term “comprising” is intended to be open andpermits but does not require the inclusion of additional elements orsteps. When the term “comprising” is used herein, the term “consistingof” is thus also encompassed and disclosed.

Where ranges are given, endpoints are included. Furthermore, it is to beunderstood that unless otherwise indicated or otherwise evident from thecontext and understanding of one of ordinary skill in the art, valuesthat are expressed as ranges can assume any specific value or subrangewithin the stated ranges in different embodiments of the invention, tothe tenth of the unit of the lower limit of the range, unless thecontext clearly dictates otherwise.

In addition, it is to be understood that any particular embodiment ofthe present invention that falls within the prior art may be explicitlyexcluded from any one or more of the claims. Since such embodiments aredeemed to be known to one of ordinary skill in the art, they may beexcluded even if the exclusion is not set forth explicitly herein. Anyparticular embodiment of the compositions of the invention (e.g., anynucleic acid or protein encoded thereby; any method of production; anymethod of use; etc.) can be excluded from any one or more claims, forany reason, whether or not related to the existence of prior art.

EXAMPLES Example 1. Preparation of Taste-Masked Formulations of SodiumPhenylbutyrate

Taste-masked materials may be prepared using the following methodology.

Drug Layering Solution

A solution of HPMC E 5 and PEG 6000 in purified water is made. Aseparate solution of sodium phenylbutyrate in purified water is alsoprepared. The two solutions are then combined to create the final druglayering solution of HPMC E 5, PEG 6000, and sodium phenylbutyrate inpurified water.

Drug Layer Coating

Cellulose pellets are preheated to 35+/−2° C. in a GPCG-1 fluid bed witha 6″ Wurster insert, and the drug layering solution is sprayed. Inletair temperature is adjusted to maintain product temperature at 35-45 Cduring coating. After spraying, the coated pellets are dried for aminimum of 5 minutes at 40° C. The product is passed through 40#-70#screen, and stored in a polyethylene bag until the next solution isprepared.

Seal Coat Solution

A seal coat solution is prepared by mixing Opadry Clear in purifiedwater for 30 minutes. The solution is passed through a 40# screen whilebeing continuously stirred.

Seal Coating

The drug layered pellets are preheated to 35+/−2° C. in the GPCG-1 fluidbed with a 6″ Wurster insert, and the seal coat solution is sprayed.Inlet air temperature is adjusted to maintain product temperature at35-45° C. during coating. After spraying, the coated pellets are driedfor a minimum of 5 minutes at 40° C. The product is passed throughscreen, and stored in a polyethylene bag until the next solution isprepared.

Taste-Mask Solution

A taste mask coating is prepared. A 2:3 parts acetone:IPA solution ismixed, and half is used to create a solution of Eudragit E PO. In aseparate beaker the other half of solution is used to homogenize talcand PEG 6000. Both solutions are then combined before being filteredthrough a 40# screen.

Taste-Mask Coating

The seal coated pellets are preheated to 27+/−2° C. in the GPCG-1 fluidbed, and the taste mask coating is sprayed using bottom spray. Inlet airtemperature is adjusted to maintain product temperature at 25-28° C.during coating. After spraying, the pellets are dried for a minimum of10 minutes at 40° C., and stored in a polyethylene bag. A formulationwith a 24 wt % taste-mask coat and 22 wt % drug load is presented inTable 2.

TABLE 2 Taste-mask coated formulation (24 wt % taste-mask coat, 22 wt %drug load) Layer Ingredient mg/g Seed core Microcrystalline cellulosepellets 443.6 Drug layer Sodium phenylbutyrate 221.8 HPMC E 5 55.5 PEG6000 5.5 (H2O) — Seal coat Opadry Clear 31.1 (H2O) — Taste-mask coatEudragit E PO 151.5 PEG 6000 15.5 Talc 75.8 (acetone) — (isopropylalcohol) —

In Vitro Dissolution Testing

A pH 6.8 potassium phosphate buffer solution (USP) was prepared, and 700mL of the solution was added to a Distek 2500 USP II (paddle)dissolution apparatus. The bath was heated to 37.5 C and 1 gm of sodiumphenylbutyrate multiparticulates was added while being agitated at 100RPM. Samples of the dissolution media (1.5 mL) were collected and drugrelease was measured with a Shimadzu Prominence-I LC-2030C 3D HPLCsystem. After the 15 minute sample was taken, 100 mL of 1 N hydrochloricacid solution was added to the dissolution vessel, and the volume wasadjusted to 900 mL by adding a pH 1.2 0.1 N HCl solution (USP). Thedissolution test continued for another 65 minutes, and data is presentedin FIG. 2.

Example 2. Preparation of a Taste-Masked Formulation of SodiumPhenylbutyrate

Taste-masked materials were prepared using the methodology described inExample 1 to achieve a formulation with a 44 wt % taste-mask coat and 16wt % drug load. This formulation was dissolution tested as described inExample 1. The details of the formulation are presented in Table 3, anddissolution data is presented in FIG. 3.

TABLE 3 Taste-mask coated formulation (44 wt % taste-mask coat, 16 wt %drug load) Layer Ingredient mg/g Seed core Microcrystalline cellulosepellets 325.3 Drug layer Sodium phenylbutyrate 162.7 HPMC E 5 40.7 PEG6000 4.1 (H2O) — Seal coat Opadry Clear 22.8 (H2O) — Taste-mask coatEudragit E PO 277.8 PEG 6000 27.7 Talc 138.9 (acetone) — (isopropylalcohol) —

Example 3. Preparation of a Taste-Masked Formulation of SodiumPhenylbutyrate

Taste-masked materials were prepared using the methodology described inExample 1, without the seal coat solution or coating steps, to achieve aformulation with a 31 wt % taste-mask coat and 47 wt % drug load. Thisformulation was dissolution tested as described in Example 1. Thedetails of the formulation are presented in Table 4, and dissolutiondata is presented in FIG. 4.

TABLE 4 Taste-mask coated formulation (31 wt % taste-mask coat, 47 wt %drug load) Layer Ingredient mg/g Seed core Microcrystalline cellulosepellets 161.4 Drug layer Sodium phenylbutyrate 473.8 HPMC E 5 47.4 PEG6000 7.1 (H2O) — Taste-mask coat Eudragit E PO 206.9 PEG 6000 20.6 Talc82.8 (acetone) — (isopropyl alcohol) —

Example 4. Preparation of a Taste-Masked Formulation of SodiumPhenylbutyrate

Taste-masked materials were prepared using the methodology described inExample 1, without the seal coat solution or coating steps, to achieve aformulation with an 18 wt % taste-mask coat and 67 wt % drug load. Thisformulation was dissolution tested as described in Example 1. Thedetails of the formulation are presented in Table 5, and dissolutiondata is presented in FIG. 5.

TABLE 5 Taste-mask coated formulation (18 wt % taste-mask coat, 67 wt %drug load) Layer Ingredient mg/g Seed core Microcrystalline cellulosepellets 73.2 Drug layer Sodium phenylbutyrate 669.5 HPMC E 5 67.0 PEG6000 6.7 (H2O) — Taste-mask coat Eudragit E PO 122.5 PEG 6000 12.2 Talc49.0 (acetone) — (isopropyl alcohol) —

Example 5. Preparation of a Taste-Masked Formulation of SodiumPhenylbutyrate

Taste-masked materials were prepared using the methodology described inExample 1, without the seal coat solution or coating steps, to achieve aformulation with a 43 wt % taste-mask coat and 47 wt % drug load. Thisformulation was dissolution tested as described in Example 1. Thedetails of the formulation are presented in Table 6, and dissolutiondata is presented in FIG. 6.

TABLE 6 Taste-mask coated formulation (43 wt % taste-mask coat, 47 wt %drug load) Layer Ingredient mg/g Seed core Microcrystalline cellulosepellets 51.2 Drug layer Sodium phenylbutyrate 468.7 HPMC E 5 46.9 PEG6000 4.7 (H2O) — Taste-mask coat Eudragit E PO 285.7 PEG 6000 28.5 Talc114.3 (acetone) — (isopropyl alcohol) —

Example 6. Preparation of a Taste-Masked Formulation of SodiumPhenylbutyrate

Taste-masked materials were prepared using the methodology described inExample 1, substituting a HPMC E 5 and PEG 6000 seal coat solution withthe Opadry seal coat solution. The change to Example 1 was used toachieve a formulation with a 23 wt % taste-mask coat and 61 wt % drugload. This formulation was dissolution tested as described in Example 1.The details of the formulation are presented in Table 7, and dissolutiondata is presented in FIG. 7.

TABLE 7 Taste-mask coated formulation (23 wt % taste-mask coat, 61 wt %drug load) Layer Ingredient mg/g Seed core Microcrystalline cellulosepellets 66.3 Drug layer Sodium phenylbutyrate 606.6 HPMC E 5 60.7 PEG6000 6.0 (H2O) Seal coat HPMC E 5 26.4 PEG 6000 3.2 (H2O) Taste-maskcoat Eudragit E PO 153.9 PEG 6000 15.4 Talc 61.5 (acetone) (isopropylalcohol)

Example 7. Preparation of a Taste-Masked Formulation of SodiumPhenylbutyrate

Taste-masked materials were prepared using the methodology described inExample 1, substituting a HPMC E 5 and PEG 6000 seal coat solution withthe Opadry seal coat solution. The change to Example 1 was used toachieve a formulation with an 43 wt % taste-mask coat and 45 wt % drugload. This formulation was dissolution tested as described in Example 1.The details of the formulation are presented in Table 8, and dissolutiondata is presented in FIG. 8.

TABLE 8 Taste-mask coated formulation (43 wt % taste-mask coat, 45 wt %drug load) Layer Ingredient mg/g Seed core Microcrystalline cellulosepellets 49.3 Drug layer Sodium phenylbutyrate 450.6 HPMC E 5 45.1 PEG6000 4.5 (H2O) Seal coat HPMC E 5 19.6 PEG 6000 2.4 (H2O) Taste-maskcoat Eudragit E PO 285.7 PEG 6000 28.5 Talc 114.3 (acetone) (isopropylalcohol)

Example 8. Reconstitution with Dosing Vehicle and Administration

A formulation of sodium phenylbutyrate, e.g., the formulation preparedin Examples 1-7, can be suspension in water with the aid of a dosingvehicle for oral administration. The dosing vehicle is first prepared byadding 2.5 tsp of THICK-IT® to 120 mL of water and agitating. To thisdosing vehicle are added 10 g of the taste-masked formulation, themixture is agitated to suspend the beads, and the entire prepared doseis swallowed by the patient. The container is rinsed twice to ensure allof the taste-masked formulation is administered by adding an additional120 mL of water, agitating to suspend any remaining formulation, andthen swallowing; this process is repeated for a total of two rinses.

Example 9. Determination of Flavor Profile

A formulation of sodium phenylbutyrate, e.g., the formulation preparedin Examples 1-7, can be tested for palatability using any appropriatetaste test known in the art, for example by a flavor profile test. Theflavor profile method uses trained evaluators, such as a panel of 1, 2,3, 4, 5, 6, 7, 8, 9, 10 or more experts, to identify, characterize, andquantify the perceived sensory attributes of a formulation.

Attributes identified by the panel are basic tastes (sweet, sour, salty,bitter, umami), aromatics (flavoring aromatics and aromatic“off-notes”), feeling factors (cooling, numbing, bite/burn, etc.), andamplitude (perception of balance and fullness). The perceived strengthor intensity of each of these attributes will be measured and assignedan appropriate value: 0 for none, 1 for slight, 2 for moderate, and 3for strong. Chemical reference standards are used to establish theintensity scale for on-going panelist calibration. Additionally, allsensations remaining in the aftertaste are measured at selectedintervals over 1, 5, 10, 15 or more minutes.

Example 10. Determination of Distribution of Sodium Phenylbutyrate inPlasma

A Phase 1, single-center, single-dose, randomized, open-label,4-sequence, 2-period, crossover study designed may be used to evaluatethe bioequivalence of a taste-masked sodium phenylbutyrate formulationto BUPHENYL® in healthy male and female volunteers in fed and fastedstates. Male and female volunteers are randomized to one of the 4sequences to determine treatment for each study period. There is aminimum 12-hour washout between periods. The washout duration isregarded as sufficient as compared with the 0.8 hour mean terminalhalf-life reported for sodium phenylbutyrate in healthy adults

At least 64 volunteers are enrolled in the study, with 16 randomized toeach of the study sequences. An informed consent form is signed beforeany study-related procedures are performed. Treatments will be balancedfor male and female volunteers.

The four treatment sequences are as follows in Table 9:

TABLE 9 Treatment Sequences for Bioequivalence Study Sequence Period 1Period 2 A sodium phenylbutyrate fed Taste-masked fed B Taste-masked fedsodium phenylbutyrate fed C sodium phenylbutyrate fasted Taste-maskedfasted D Taste-masked fasted sodium phenylbutyrate fasted

Volunteers check into the study center at least 8 hours prior to Period1 (Day-1) and remain at the study center for the 2 consecutive treatmentperiods, including remaining at the study center during the washoutbetween Period 1 and Period 2 (Day 2). For fasted sequences, volunteersare required to fast for a minimum of 8 hours prior to initiatingtreatment (BUPHENYL® or the taste-masked formulation of sodiumphenylbutyrate administration) for each period. For fed sequences,volunteers consume a United States Food and Drug Administration (FDA)standard high calorie, high fat breakfast beginning 30 minutes prior toadministration of a composition prior in each period. Volunteers receiveoral doses of 500 mg taste-masked formulation (per FDA Draft Guidance onSodium Phenylbutyrate bioequivalence; May 2009). At each dosing time,the formulation is dissolved in 6 ounces of room temperature tap waterby mixing gently. Volunteers are instructed to ingest the solutionimmediately.

Each treatment period lasts for 1 day. Blood draw schedules facilitatemeasurement of plasma phenylbutyrate levels at baseline and postdose foreach period, and results are used to estimate the non-compartmentalpharmacokinetic (PK) parameters. Blood samples for measurement of plasmaconcentrations of phenylbutyrate and phenylbutyrate metabolites areobtained in each study period at predose and at 0.25, 0.5, 0.75, 1.0,1.5, 2.0, 2.5, 3.0, 4.0, and 8.0 hours postdose. The concentration ofphenylbutyrate and phenylbutyrate metabolites in blood samples aremeasured using a validated liquid chromatography-tandem massspectroscopy (LC-MS/MS) method. Blood samples may be stored for PKanalyses for up to 12 months after the end of the study.

90% bioequivalence intervals are built comparing phenylbutyrate andphenylbutyrate metabolites in volunteers receiving either thetaste-masked formulation or BUPHENYL® in fed (Sequences A and B) andfasted (Sequences C and D) states.

Safety is evaluated on the basis of incidence of adverse events andclinically significant changes in laboratory test results (chemistry,hematology, and urinalysis).

Other Embodiments

It is to be understood that while the present disclosure has beendescribed in conjunction with the detailed description thereof, theforegoing description is intended to illustrate and not limit the scopeof the present disclosure, which is defined by the scope of the appendedclaims. Other aspects, advantages, and alterations are within the scopeof the following claims.

What is claimed:
 1. A method of treating a urea cycle disorder, themethod comprising administering a therapeutically effective amount ofsodium phenylbutyrate in a pharmaceutical composition to a subject inneed thereof, wherein the pharmaceutical composition comprises aplurality of taste-masked, layered particles, and wherein thepharmaceutical composition comprises greater than 60% by total weight ofthe sodium phenylbutyrate.
 2. The method of claim 1, wherein, uponadministration to the subject, the pharmaceutical composition isbioequivalent to compared to a sodium phenylbutyrate formulation thatdoes not comprise a taste-mask coating.
 3. The method of claim 1,wherein the pharmaceutical composition is administered in combinationwith a dosing vehicle.
 4. The method of claim 3, wherein the dosingvehicle comprises modified food starch, maltodextrin, or a combinationthereof.
 5. The method of claim 4, wherein the modified food starch ismodified corn starch.
 6. The method of claim 1, wherein thetherapeutically effective amount is 450-600 mg/kg/day in subjectsweighing less than 20 kg or 9.9-13.0 g/m²/day in larger subjects.
 7. Themethod of claim 1, wherein the subject is on a protein restricted diet.8. The method of claim 1, further comprising administering essentialamino acids to the subject.
 9. The method of claim 1, wherein thetherapeutically effective amount is administered in equally dividedamounts with each meal or feeding.
 10. The method of claim 1, whereinthe administering is oral.
 11. The method of claim 1, wherein thetherapeutically effective amount is administered three to six times perday.
 12. The method of claim 1, wherein the urea cycle disorder iscaused by a mutation in N-acetylglutamate synthetase, carbamoylphosphate synthetase I, ornithine transcarbamylase, argininosuccinicacid sythetase, argininosuccinic acid lyase, or arginase.
 13. The methodof claim 1, wherein the plurality has a volume-based particle sizedistribution in which at least 90% of the layered particles in theplurality of layered particles are smaller than 500 μm.
 14. The methodof claim 1, wherein the subject is a human.
 15. The method of claim 1,wherein the administration results in removal of excess ammonia from theblood of the subject.
 16. A method of treating maple syrup urinedisease, the method comprising administering a therapeutically effectiveamount of sodium phenylbutyrate in a pharmaceutical composition to asubject in need thereof, wherein the pharmaceutical compositioncomprises a plurality of taste-masked, layered particles, and whereinthe pharmaceutical composition comprises greater than 60% by totalweight of the sodium phenylbutyrate.
 17. The method of claim 16, whereinthe pharmaceutical composition is administered in combination with adosing vehicle.
 18. The method of claim 17, wherein the dosing vehiclecomprises modified food starch, maltodextrin, or a combination thereof.19. The method of claim 18, wherein the modified food starch is modifiedcorn starch.
 20. The method of claim 16, wherein the therapeuticallyeffective amount is 450-600 mg/kg/day in subjects weighing less than 20kg or 9.9-13.0 g/m²/day in larger subjects.
 21. The method of claim 16,wherein the therapeutically effective amount is administered in equallydivided amounts with each meal or feeding.
 22. The method of claim 16,wherein the administering is oral.
 23. The method of claim 16, whereinthe therapeutically effective amount is administered three to twelvetimes per day.
 24. The method of claim 16, wherein the plurality has avolume-based particle size distribution in which at least 90% of thelayered particles in the plurality of layered particles are smaller than500 μm.
 25. The method of claim 16, wherein the subject is a human. 26.The method of claim 16, wherein the therapeutically effective amount issufficient to lower the plasma level of a branched chain amino acid(BCAA).
 27. The method of claim 26, wherein the BCAA is leucine, and thelevel is lowered to 200-500 μmol/L.
 28. The method of claim 26, whereinthe BCAA is isoleucine, and the level is lowered to 100-200 μmol/L. 29.The method of claim 26, wherein the BCAA is valine, and the level islowered to 100-300 μmol/L.